-LRB- CNN -RRB- -- In this case , BFF could stand for `` Bigtime Famous Friends . ''

The first lady turns 50 on Friday , and it 's being reported that she will be serenaded by singer Beyonce for the occasion . The White House is not commenting on whether the singer will be in attendance for Michelle Obama 's birthday party , but it 's well known that the pair are friends .

The superstar performed the Etta James classic `` At Last '' at President Obama 's first inaugural ball and teamed up with Michelle Obama for her initiative to get children more active . Who can forget FLOTUS dancing to Beyonce 's `` Move Your Body '' exercise theme ? Even their spouses are friends . Rapper Jay Z changed the lyrics to his rap song to say `` I 've got 99 problems but Mitt ai n't one '' during an Obama fundraiser .

In July , the first lady and daughters Malia and Sasha attended a Beyonce concert in Chicago . The singer even once wrote an open letter of admiration : `` Michelle , thank you so much for every single thing that you do for us . I am proud to have my daughter grow up in a world where she has people like you to look up to . ''

Michelle Obama responded , '' @Beyonce Thank you for the beautiful letter and for being a role model who kids everywhere can look up to . -- mo ''

Awwwww !

Their friendship has not been without controversy , however .

Some Christian mothers were reportedly upset over FLOTUS teaming up with Beyonce because of the singer 's `` booty shaking '' and revealing outfits . Writing for the Daily Beast , journalist Allison Samuels noted that there was `` the unfortunate conundrum posed for Mrs. Obama . ''

`` When BeyoncÃ © goes into the studio to record an album for her millions of fans , she 's not thinking about her friendship with the first lady ; she 's thinking about what 's hot , what 's edgy , and what will sell to the masses , '' Samuels wrote . `` That surely must have been her mindset when she recorded the controversial lyrics single `` bow down b ** ches '' for her new album earlier this year . ''

Demetria L. Lucas from the Root wrote , `` This love fest has gone too far for my liking . I 'm no one -LRB- and neither are you -RRB- to police the first lady 's musical tastes , but this continued public endorsement of Houston 's Finest rubs me the wrong way . I am not a Bey hater , but I am an observant onlooker . ''

Powerful friends can attract powerful opinions .

@highlight

First lady Michelle Obama and singer Beyonce are friends

@highlight

Beyonce may appear at Obama 's 50th birthday party

@highlight

Not everyone is happy about their relationship